In modern technical applications, circuit breakers are commonly used. Especially, circuit breakers can be used to circuit switching of high currents and powers respectively, for instance a circuit switching of currents as high as 70 kA and even higher. It is known to equip such circuit breakers with safety devices such as for instance an overload protection and/or a short-circuit protection and the according trigger switches. The overall safety during the usage of high electrical currents and/or powers can therefore be improved by a usage of such circuit breakers.
Modern circuit breakers generally comprise an operating lever for a manipulation by the operator, in most cases movable at least between an OFF-position and an ON-position. Internally, the switching of the electrical current is achieved by a contact system, the contact system usually comprising one or more pairs of fixed and movable contacts. A latching mechanism is provided in between, mechanically connected both to the operating handle and the contact system. Therefore, a manipulation of the operating lever by the operator results in a change in the contact system, for instance, a change of the position of the operating between its OFF-position and its ON-position results in a closing of the contacts of the contact system.
During the movement of the operating handle into its ON-position, in addition to the closing of the contacts of the contact system also an arming of the protection system(s) in the circuit breaker is necessary. Especially after the occurrence of a tripping incident, for instance an overcurrent or a short-circuit, this arming needs a reset of the circuit breaker, especially of the latching mechanism of the circuit breaker. In such a reset, especially of the latching mechanism, also the normal operation of the circuit breaker, e.g. induced by switching the operating lever from its OFF-position in its ON-position, can be prepared. Without a reset of the latching mechanism, the latching mechanism cannot be activated in a subsequent movement of the operating lever in its ON-position and the contact system of the circuit breaker cannot be closed and in addition the protection systems of the circuit breaker cannot be armed.
If a circuit breaker is switched on and its operating handle is accordingly moved into the ON-position, all movements of the latching mechanism and especially of the contacts of the electrical contact system have to be stopped at the end of the switching-on procedure. Especially an immediate activation of any armed safety device has to be prohibited. An unintentional interruption of the flow of current through the circuit breaker can for instance lead to a damage of a consumer load in the downstream electrical circuit.
One possible solution according to the state of the art is to disable the safety devices at a short period at the beginning of the operation of the circuit breaker. To hinder an unintentional triggering of a safety device, it is further known in circuit breakers according to the state of the art to provide for instance strong springs to solve the aforementioned issue. However, these stronger springs can lead to higher releasing forces for the safety devices. The overall safety for such circuit breakers could therefore be decreased. It is known in the state of the art to use longer lever-arms for the safety devices to solve this issue, but this leads to a larger size of the circuit breakers. Therefore, small and compact circuit breakers cannot be provided.